First of all, wash the sweet potato that needs to be steamed and cut it into pieces, preferably not too thick, otherwise it will be uncooked.

Secondly, open the heating bag in the box and add water, put the prepared sweet potatoes on the box and cover it.

Finally, when the heating bag no longer keeps heating, you can open the lid and poke the sweet potato with chopsticks. If it is not cooked, add the lid to continue the stew. The above is how to steam sweet potatoes in a heated lunch box.